Friction bolster spring



Sept. 23, 1941. w. G. KRAUsER 2,256,485

FRICTION BOLSTER SPRING Filed Nov. 18, 1959 Patented Sept. 23, i941 UNITED STATES PATENT OFFICE FRICTION BOLSTER SPREQTG Webb G. Krauser, Montreal, Quebec, Canada, as-V signor to Cardwell-Westinghouse Company, a corporation of Delaware Application November 18, 1939, Serial No. 305,147

8 Claims.

This invention relates to railway car bolster supporting units and one of the principal objects of the invention is the provision of a new and improved spring unit having a novel combination of friction and yielding means for cushioning the vibration of a spring assembly.

Another object of the invention is the provision l of a new and improved spring unit so constructed that it may have a limited lateral flexing movement together with novel means for dampening the vibration of the spring assembly with which it is employed.

A further object of the invention is the provision of a new and improved bolster springunit that is so constructed that free movement is provided during its initial compression but frictional resistance is introduced for resisting further compression and for dampening free vibration of the spring beyond a predetermined limit.

A still further object of the invention jis the provision of a new and improved spring unit that is simple in construction, efficient in operation, easily assembled and that is not likely to become deranged or get out of order.

Other and further-objects and advantages of the invention will appear from the followingV deseription, taken in connection with the accompanying drawing, in which- Fig. 1 is a side elevation of a Vehicle truck, with parts broken away and parts omitted for the sake of clearness, and showing the invention in position therein;

Fig. 2 is a side elevation of the invention; Fig. 3 is a top plan view thereof, with parts broken away; and

Fig. 4 is a vertical section thereof. It is desirable that the mechanism in spring assemblies for railway cars be so constructed that out utilizing this frictional resistance in a load supporting mechanism, the light loads would be supported by springs so stiff as to afford a very small amount of resilient movement. An assembly that would have sufficient capacity to support a full load without friction mechanism would be so stiff as to afford little or no resilient movement for light loads.

The present invention seeks to remedy this difficulty by the provision of friction mechanism in the assembly that is inactive during the initial compression of the springs ofthe assembly.

Referring now to the drawing, the reference character I0 vdesignates a railway truck having a side frame il `provided with the bolster opening I2 within which the bolster i3 extends and is movable vertically therein. The bolster i3 is supported by the spring assembly lll, as is usual in such constructions. f Since the details of the truck and bolster construction constitute no part of the present invention, it is not thought necessary to further illustrate or described the same.

The spring Aassemblyv I5 Acomprises a plurality of free acting helical springs l5 and one or more frictional spring units I6 at each end of the car. The spring unit l5 comprises an outer spring l'i which is provided on its inner circumference with a friction surface I8, as clearly shown in Fig. 4 of the drawing. The spring l'l, may, if desired, be rectangular in cross-section and its inner friction surface is adapted to be engaged by a plurality of friction shoes I9 at one end only of the spring. Forv convenience of description, the shoes i9 will be considered as engaging what maybe considered the'upper 4turns of the spring l'l. Any suitable number of shoes may be employed. In the form of the construction selected to illustrate one embodiment of the invention, three shoes having their longitudinal center lines separated apart are employed. The outer faces 2l of these shoes are in the form of segments of cylinders corresponding to the curvature of the inner surface I8 of the spring n.

The spring l'! is adapted to seat on, and is preferably rigidly connected to, a follower or base plate 22as by being welded thereto as shown at 20 in Fig. 4. This follower is provided with a circular ange 23 for engaging the interior of the fspring. The central portion of the plate 22 is depressed as at 24 and the depressed portion is provided with an opening 25 through which the i vided with a plurality of inclined friction faces 29 that are adapted to frictionally engage inclined or wedging faces 3| on the upper surface of an inwardly extending projection 3B on the shoes I9. These surfaces are planar surfaces as indicated in Fig. 3.

The parts are so constructed that when the spring is compressed, the inclined wedging faces 29 and 3| of the shoes and follower plate cooperate to force the shoes I9 radially outwardly into frictional engagement with the inner surface of the outer spring I1.

Suitable means are providedfor returning the follower plate 21 and shoes I9 to their normal inoperative position after release. Any suitable mechanism may be used for this purpose. As shown, an inner spring 32 is employed, the lower end of which extends about the hub or depression 24 of the lower follower plate 22 which positions this spring on the plate 22. The upper end of the spring 32 seats against a spring seat, wedge plate or block 33 having wedge faces 34 thereon for engaging corresponding wedge faces 35 on the lower surface of the inward extension 3U of the shoes I9, Fig. 4. The shoes I9 engage only a portion of the turns of the springs I1. As shown in Fig. 4, they engage only the turns of the upper portion of the spring.

Upon compression of the unit beyond a Certain amount, as will presently appear, the thrust or follower member 21 will be formed downwardly relative to the spring and since the spring 32 operates against the wedge member 33 for resisting this movement, the cooperating wedging faces on the shoes and plates force the shoes radially outwardly into frictional resistance with the inner surface of the outer spring thereby resisting further compression of the unit.

In the operation of the device, upon initial compression of the spring I1, the lower or free turns 36 of the spring will have a free or resilient movement while the upper turns will not move relatively to each other due to the frictional resistance between the shoes and those turns. Upon further compression, however, the lower turns 33 will come in contact with each other, that is, will go solid thereby resisting any further downward movement of the follower 21 and further compression will be resisted by the friction between the shoes andethe upper turns of the spring l1. These turns will also gradually be moved toward each other until they go solid and under abnormal loads, the follower 21 may move into contact with the upper end of the spring thus forming a solid column. This latter condition, however, very seldom, if ever,

It will thus be seen that the spring assembly is free to move resiliently through a predetermined distance for resiliently supporting light loads and that frictional resistance is provided for increasing the capacity of the assembly for supporting full loads. Furthermore, there being no rigid members for guiding the springs in their movement, they are free to cant more or less as occasion may require, that is, they may flex laterally to a certain extent to accommodate the limited lateral movement of the bolster when the truck travels around curves and the like.

It is thought from the foregoing, taken in connection with the accompanying drawing, that the construction and operation of my device will be apparent to those skilled in the art and that changes in shape, size, proportion or detail may be made without departing from the spirit or scope of the appended claims.

I claim as my invention:

1. In a spring assembly for supporting a railway truck bolster, a friction spring unit comprising a spring, friction shoes for frictionally engaging the interior surface of a limited number of turns at one end only of said spring, each shoe being provided with an inclined face on its outer end, said inclined faces extending outwardly `beyond the adjacent end of the spring when the unit is expanded, a thrust member having wedging faces engaging the inclined faces of said shoes for forcing said shoes outwardly into frictional engagement with said spring, a wedge block having wedging faces engaging corresponding wedging faces on said shoes for forcing said shoes outwardly when the unit is compressed, and a spring engaging said block for resiliently resisting inward movement of said shoes and block, said unit being so constructed that the same may be flexed laterally.

2. In a friction spring unit, a helical spring, means frictionally engaging the turns at one end portion only of said spring for frictionally resisting final compression of said spring and constituting the sole means for frictionally resisting the compression of said unit, the remaining turns of said spring being free to function as a freely acting supporting spring means, the unit being free to ex laterally.

3. In a friction spring unit, a helical spring having a plurality of its turns at one end only free acting for resiliently supporting light loads and for providing for limiting lateral movement of said load, and means for frictionally engaging the remainder of said turns at the opposite end of said unit for frictionally resisting the compression of said spring for supporting heavy loads, said means constituting the sole frictional resistance to the final compression movement of said unit.

4. In a friction spring unit, a helical spring, having turns rectangular in cross section, friction shoes engaging the inner surface of said turns at one end only of said unit, said shoes having wedging faces at their outer ends extending beyond the adjacent end of said spring, wedging faces on the adjacent follower engaging the wedging faces on said shoes for forcing said shoes radially outwardly into frictional contact with said spring upon compression thereof, resilient means for resisting the longitudinal inward movement of said shoes, certain turns of said spring being free to move both vertically and horizontally whereby said unit will have a limited lateral fiexing movement and light loads will be supported by said free turns but after the free turns go solid, heavier loads will be movably supported by the frictional resistance of said shoes and spring.

5. In a friction spring unit, an upper follower, a lower follower, a spring seated on and rigidly connected to the lower follower, friction mechanism including friction shoes engaging the interior of said spr-ing at its upper end portion only and engaging said upper follower, cooperating wedge surfaces on said shoes and said upper follower for forcing said shoes radially outwardly when said unit is compressed, said wedging surfaces extending above said spring when the unit is expanded, and an inner spring engaging said lower follower and said friction mechanism for resisting the inward movement of said mechanism, said unit being flexible laterally to a limited extent.

6. A spring unit comprising an upper follower, a lower follower, a spring, said spring constituting the outermost portion of the unit between said followers, friction shoes engaging the interior of one end only of said spring, a plurality of turns of said spring at the opposite end of said spring being free-acting whereby said unit may ex laterally in operation, and Wedge faces on one of said followers for engaging corresponding inclined faces on the outer ends of said shoes for forcing said shoes outward into frictional engagement with said spring when said spring is compressed.

7. In a spring assembly, a helical spring having its turns rectangular in cross-section, a plurality of friction shoes engaging the interior circumference of said spring at one end only thereof, said spring constituting the sole means surrounding said shoes, each of said shoes having inwardly extending inner and outer converging friction faces, the outwardly converging faces extending outwardly beyond the adjacent end of the spring, a thrust member having inclined fricsaid shoes, said unit being flexible laterally, each shoe having a wedging surface opposite the end turns of said spring, a thrust member having an inclined face for engaging the wedging surfaces of said shoes for forcing said shoes radially outwardly into frictional engagement with said spring, and means engaging said shoes for yieldingly resisting the inward movement of said shoes.

WEBB G. KRAUSER. 

